1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "media/formats/mp2t/ts_section_pmt.h"
6
7#include <map>
8
9#include "base/logging.h"
10#include "media/base/bit_reader.h"
11#include "media/formats/mp2t/mp2t_common.h"
12
13namespace media {
14namespace mp2t {
15
16TsSectionPmt::TsSectionPmt(const RegisterPesCb& register_pes_cb)
17    : register_pes_cb_(register_pes_cb) {
18}
19
20TsSectionPmt::~TsSectionPmt() {
21}
22
23bool TsSectionPmt::ParsePsiSection(BitReader* bit_reader) {
24  // Read up to |last_section_number|.
25  int table_id;
26  int section_syntax_indicator;
27  int dummy_zero;
28  int reserved;
29  int section_length;
30  int program_number;
31  int version_number;
32  int current_next_indicator;
33  int section_number;
34  int last_section_number;
35  RCHECK(bit_reader->ReadBits(8, &table_id));
36  RCHECK(bit_reader->ReadBits(1, &section_syntax_indicator));
37  RCHECK(bit_reader->ReadBits(1, &dummy_zero));
38  RCHECK(bit_reader->ReadBits(2, &reserved));
39  RCHECK(bit_reader->ReadBits(12, &section_length));
40  int section_start_marker = bit_reader->bits_available() / 8;
41
42  RCHECK(bit_reader->ReadBits(16, &program_number));
43  RCHECK(bit_reader->ReadBits(2, &reserved));
44  RCHECK(bit_reader->ReadBits(5, &version_number));
45  RCHECK(bit_reader->ReadBits(1, &current_next_indicator));
46  RCHECK(bit_reader->ReadBits(8, &section_number));
47  RCHECK(bit_reader->ReadBits(8, &last_section_number));
48
49  // Perform a few verifications:
50  // - table ID should be 2 for a PMT.
51  // - section_syntax_indicator should be one.
52  // - section length should not exceed 1021.
53  RCHECK(table_id == 0x2);
54  RCHECK(section_syntax_indicator);
55  RCHECK(!dummy_zero);
56  RCHECK(section_length <= 1021);
57  RCHECK(section_number == 0);
58  RCHECK(last_section_number == 0);
59
60  // TODO(damienv):
61  // Verify that there is no mismatch between the program number
62  // and the program number that was provided in a PAT for the current PMT.
63
64  // Read the end of the fixed length section.
65  int pcr_pid;
66  int program_info_length;
67  RCHECK(bit_reader->ReadBits(3, &reserved));
68  RCHECK(bit_reader->ReadBits(13, &pcr_pid));
69  RCHECK(bit_reader->ReadBits(4, &reserved));
70  RCHECK(bit_reader->ReadBits(12, &program_info_length));
71  RCHECK(program_info_length < 1024);
72
73  // Read the program info descriptor.
74  // TODO(damienv): check wether any of the descriptors could be useful.
75  // Defined in section 2.6 of ISO-13818.
76  RCHECK(bit_reader->SkipBits(8 * program_info_length));
77
78  // Read the ES description table.
79  // The end of the PID map if 4 bytes away from the end of the section
80  // (4 bytes = size of the CRC).
81  int pid_map_end_marker = section_start_marker - section_length + 4;
82  std::map<int, int> pid_map;
83  while (bit_reader->bits_available() > 8 * pid_map_end_marker) {
84    int stream_type;
85    int reserved;
86    int pid_es;
87    int es_info_length;
88    RCHECK(bit_reader->ReadBits(8, &stream_type));
89    RCHECK(bit_reader->ReadBits(3, &reserved));
90    RCHECK(bit_reader->ReadBits(13, &pid_es));
91    RCHECK(bit_reader->ReadBits(4, &reserved));
92    RCHECK(bit_reader->ReadBits(12, &es_info_length));
93
94    // Do not register the PID right away.
95    // Wait for the end of the section to be fully parsed
96    // to make sure there is no error.
97    pid_map.insert(std::pair<int, int>(pid_es, stream_type));
98
99    // Read the ES info descriptors.
100    // TODO(damienv): check wether any of the descriptors could be useful.
101    // Defined in section 2.6 of ISO-13818.
102    RCHECK(bit_reader->SkipBits(8 * es_info_length));
103  }
104
105  // Read the CRC.
106  int crc32;
107  RCHECK(bit_reader->ReadBits(32, &crc32));
108
109  // Once the PMT has been proved to be correct, register the PIDs.
110  for (std::map<int, int>::iterator it = pid_map.begin();
111       it != pid_map.end(); ++it)
112    register_pes_cb_.Run(it->first, it->second);
113
114  return true;
115}
116
117void TsSectionPmt::ResetPsiSection() {
118}
119
120}  // namespace mp2t
121}  // namespace media
122
123